This invention relates to stable cathodes and, in particular, to a mechanism for retarding nickel oxide loss in the cathode of a molten carbonate fuel cell.
Cathodes for use in molten carbonate fuel cells generally employ lithiated nickel oxide as the cathode constituent. During long term operation of the fuel cell it is found that dissolution of nickel oxide and precipation of the nickel occurs. As a result, the cathode is consumed at the cathode-electrolyte interface, thereby greatly decreasing the cathode surface area. Furthermore, nickel precipitates into the matrix increasing the likelihood that electrical shorting of the cell may occur.
In a molten carbonate fuel cell the severity of the above effects has been found to be influenced by the gas composition used, the matrix thickness, load conditions and other cell characteristics. However, to date, elimination of these effects has not been possible under normal cell operating conditions. Also, while attempts have been made to develop alternative cathode materials, satisfactory substitute materials have not as yet been found.
It is therefore a primary object of the present invention to provide a mechanism for retarding nickel loss in a nickel oxide cathode.
It is a further object of the present invention to provide a mechanism for retarding nickel dissolution and nickel precipitation in a nickel oxide cathode electrode.